Greater raphe nuclei (RN) serotonin_1A binding potential predicted higher suicidal ideation and more lethal suicidal behavior, a recent study found. In a prospective 2-year study, a cohort of 100 patients presenting for treatment of a major depressive episode of at least moderate severity underwent positron emission tomography, using a serotonin_1A agonist; a subset of 50 patients also underwent imaging with a serotonin transporter radioligand. Researchers found:

• Of the 100 patients undergoing follow-up for more than 2 years (39 men; 61 women; mean [SD] age, 40.2 [11.2] years), 15 made suicide attempts, including 2 who died by suicide.

• Higher RN serotonin_1A binding potential predicted more suicidal ideation at 3 and 12 months and greater lethality of subsequent suicidal behavior.

• Contrary to hypotheses, suicidal intent was not predicted by serotonin_1A binding potential in any brain region, and midbrain serotonin transporter binding potential did not predict future attempts, possibly owing to low power.

Citation: Oquendo MA, Galfalvy H, Sullivan GM, et al. Positron emission tomographic imaging of the serotonergic system and prediction of risk and lethality of future suicidal behavior. [Published online ahead of print July 27, 2016]. JAMA Psychiatry. doi:10.1001/jamapsychiatry.2016.1478.